Electrical



May 2l, 1929. w. DUBILIER 1,713,857

ELECTRICAL'A CONDENSER Filed March 1, 1924 2 Sheets-Sheet 1 A A A A illumini INVENTOR ATTORNEY Patented May 21, 1929.

UNITED STATES 1,713,867 ParafiarI carica.

WILLIAM DUBILIER, or NEW YORK, N. Y., AssIcNoR To DUL'IEB 'NDENSER coa- PoRA'rIoN, A CORPGRATIQNOF DELAWARE!" ELECTRICAL CONDENSER.

Application tiled March l, 1924.l'Seria1vI-To'. 696,185.'

My invention relates toA electrical condensers and has for its object to provide an electrical condenser involving the-use of a minimum amount of dielectric materia-l so arranged and disposed in connection with.

conducting plates, ast-o xproduce-assimple struct-ure capable of use in high potential high frequency circuits where it is important to employ a condenser having minimum losses and with brush discharges eliminated.

Another object isto provide a condenserV therethrough will follow a path substan tially at right angles to the plane offmany of the conducting plates therein, whereby the electrical'resistance of thecondenser is greatlyreduced.

Further objects and ladvantages of the invention will be in part obvious and in part specifically pointed out in the following` description which, taken in. connection with* the accompanying drawings discloses'a -preferred embodiment thereof. 'Such embodi-fz- Athe fact that :the flo'w of current therein is ltransverse' Ito the plane of the metallic plates nient, however, is to be considered merely illustrative of its principle. The underlying electrical principles of the present invention are the same as those.

set forth in m copending application Serial No, 472,105, fi ed May 24, 1921. this case now granted lWarch 2nd, 1926, wherein is vdisclosed a condenser consisting of alternate layers of mica and metal foil, the intermediate layers of foil being isolated one from another by the adjacent sheets of mica. By such a construction there is produced a condenser eapable of withstanding high poten.

having matured into Patent No. 1,575,044,-

'electric material; For eX'am'ple,&an ordinary condenser comprising falternate -layers of metal` foil, and mica of ia" certain thickness maybe entirely. satisfactory-.and .may show no appreciable fbrush discharge: with' animpressed potential of :1000 i volts.-

,.Bydoubling the thickness'o the layers of mica the condenser maybe capable of withstanding 2000 volts,butin the-latter instancea-nappreciable brush:- e-.discharge nx'night :oocur.

" Likewise-1 by .tilipling vand iquadrupling the thickness 'of the- Inicia? fthe-breakdown Moltage may beiinereased', :bultfin ieaeh succeeding case the probability..-ofbrush.discharge is 'rapidly increasing. By the'provision of'intermediate isolated or'whatmay beltermed floating .metallicf;plate`s, :the total :impressed potential is divided-betweentheseveral plates sothat'the: potential-across any one layer of dieleetric'is onl-y afraction of the tot-al." fIt -fhas been= conclusivelyffestablished by experiment that the ibr'ushl ldischarge is thusf ,rre'atliyt decreased iwithout any increase in-Ithe :amount-'of dielectric material required for a given'rcapacity and potential, :as compared withoondensers heretofore known. Anotherimport'ant advantage inherent in this type of condense# arises `from artl 'I will 1 illustrate-thelatter by 'reference to my U. S. Patent No. 1,229,915 dated'J une 12, 1917, whiehtshows a type 'of high tension power condenser used in practically all commercial installations, particularly in the radio field, throughout the world.":In this construction sections are employed, each see- 'tion-'made lup ofaplurality of conducting plates or sheets connecte'din parallel andscveral Vsuch sections connected inseries. The number-of sheets per section'and the number of sections arranged in series will depend upon the desired electrostatic capacity and the appliedvoltage. In this method of Construction the total resistance of the eondenserf is.-equal.to the sum-of the resistanees ofitheisections: this may be objectionable. Furthermore, a complicated system of soldering the conducting sheets of each section together and of soldering the various sections in series, is necessary and a further disadvantage is the difficulty in adjusting4 the total capacity of the condenser.

My present invention -eliminatesmany of the difficulties of the foregoing construction; particularly' the. excessiveuohmicire- --sistanc'e offtherplates inithesections, and consists A'ofmaking-up the complete condenser ofeseetions, 'each one of' which.` consists of :.manyiindependentconducting -sheets 1 `and the necessary.' dielectric and-'then connecting these sections. in parallel. Itshould be:

'.iuiotedthat in'the'condensers-of the prior art the sections `contained conducting -Jsheets iuconneetediin parallel, and that the sections were `iconnected in-series, but 4that with the present invention .this procedure is reversed. Allvherendesira'ble to -meet eertain- Working 2.9 conditions, I imay construct. afcondenser in accordance withV the .present invention by arranginga plurality of sections iu-A series, '(ea'ch-seeti'on :having awplurality of:.1inde .-pendently conducting plates) .'in:groups of ISO-sections and: then 'arrangingthese groups of -sectionsrin parallel.A This a-rrangementincreases .the creepagedistancei as. hereinafter described. v

With'condensers ofthe prior art- I;have ==found from practice that iftwo eondensers :I are madefupl ofv different electrostatic zeapac- .itieslbut-V :employing 7:the same-'materials throughout, that'thecondenserlof largerfca pacityf-wilbbreakdownuat a lowervolt-age 401 thanthe one of smaller capacity, and I find `ifromf practice' .f that with v:condensers: construeted inaccordance with the presentiin-L ventionthat this detect is largely overcome` In the aceompanyuig dra\\f1ngs,-wh1eh are largely diagrammatic, :and in'whleh some of theparts 'are widely separated 'for the .-sake' of clarity,

. Figure Lshows one of the dielectric plates havinga conducting coating as `used in the sections;

y Figure. 2 is a. diagram. of a complete sec- .tion showing the arrangement of the di- ..electric =plates therein having .thereon con- .ducting coatingsfthese coatings being herevinafter referred to as4 conducting plates or I.'foils;

f Figure 3 is a diagrammatic View of afseetion similar to that shown in Figure 2, but- .nmoditied by the inter-position of-metallie I plates vor blocks;

- Figure 4 is a'diagram illustrating-What I term -creepage distance around 'the edges of ,one of the-sections shown in Figure 2 Y or3;

'Figure 5:'is a diagramfshowing Atwo of sections, constructed as shown in Figure H .wn-3,- arranged in series forthel purpose of incre sing the creepage distance;

Figure 6 is a diagram showing eight sections, Figure. 2,.assembled to v:term a c omplete condenser unit;

Figure'? is a diagram showing a plurali-ty of complete sections of the type shown in Figure 2 or 3, arranged in series multiple between the y main terminals of the condenser,

.Figure 8 isa sectional side vicw'ot a completev condenser constructed -in accordance :with my invention, and n .'-Figure 9 is a view partlyfin cross-seetion 'of the condenser shown in Figure 8. For the: sake of illustration I- willffirst describe ansection for a condenser as commonly eniployediu Aconnection with radioapparatus and particularly adapted to transmitting sets. In such sections finica -is employed usually for the dielectricsheets-.andi-.mica sheets l of suitable thickness-and about "2." square may be employed.

The mica'sheets havewsecured to .them upon one or both sides a metallic coating 2.

.This may he appliedl in' an .'-suitable.inannei-.andv foil of .suitablethiekness is-often used. Amargin orfreesborderuabout l/L of an inch wide maybe leftall aroundthe foil, asshowu in-Figure ;1.

A plurality of sheets ofvmiea,forinstanc 2O sheets, containing the :conducting plates `orzlfoils are assembled under 'heavy pres- --:sure to form a .-seetion shown' (with the parts widelyseparated) v:in Figure 2, in which heavy lines, one .ofr-ivhiclris indi- ;catedby the numeral- .1, represent-themica :-sheets andl 2 the conducting-sl1eets or foils.

'Afterft-hese platt-:shave beenv assembled, end blocks 3 and 4fpfumetal may. beeplaeed against the section. I' Theseend blocks form :the clectrical-terminalsfurthe section and v serve to:mechanically.strengthen'the ssannr,

-Ibesides serving to. radiateE heat from-.the :section Forthepurposes of this description I dcsire that the word section be understood to embrace the complete group of foil' and mica plates together with the blocks 3 and I 4, as shown in Figure 2, where I have-designated the complete section by the numeral 5.

In'Figure 3 Ifshow a modified form of section. -I'Iere the total number of'mica and foil sheets Aare dividedinto-twoor more groups, 6, 7 andl S 'and interposed between these arethe-motal blocks 9 and l0 which, in addition to the metal blocks 3 and 4, constitute the complete unit. By this :arrange- .ment I inereasethe creepage distance across l'the Vunit from block 3 to .block 4 forreasons that will hereinafter more fully appear. l

. These separator membersfor :blocks also. serre to'con-duet heat a\vay=froni:the plates of the #section The metal blocks v3 and l such as used at the-sidesfof each-section and :the blocks 9 and 10 which may be used in the sections,

.fare preferablyotthe same surface area as altheplates i2i-.By :having allv'of the con- :ducting material vin the fcondenser of substantially thefsamesurface'larea I find the electrical strains are more .evenly divided and the condenser umts, when assembled and lo; clamped, as hereinafter described, -are bet-V r :ter-able `to withstand .thervery 'great pressure that is `appliedrto them.

.-.fs It nowx-becomes-'necessary to `consider a very important factor .'inl` 'connection` with these., sections-.iwhich-is :that I term the ii thecondenser consisted loffa single section as shown in Figure 4, (the main circuit being 4.connected to the--blocks'lB and 4:) that in case the distance across. the outer lface of the insul-ation between=the blocksis not suliiciently wlarge, =the lcurrent will'A jump 'around the edges of the section at-some'pointfrom block to.bloclr, .thus causing an arc or spark that wouldfbe objectionable :Actual sparking'or -.tan'eev across the'section. v

The creepagev .distance-er path 'will be -.acrosssox`ne.:certain point'f'in the section.

; Theoretically, this will; be theshortest dis- ",tance -across'the :outer-surface of thesections between theblocks 3 and and usually cannot be. determined -without subjectingithesection's to an actual electrical test. For the;.Sake of illustration, it will be pre- 'sumed .--that this creepage distance in thecase of the section shown in Figure ltis in- ,..dicated by t-he dotted line lland that the y ing themetallic blocks 9 and 10 in length of this path may be taken as onequar ter inch on each side face 'of thesection and one-tenth inch across the top thereof, making` a total of .6".

.It will no 'wI bev seen that I can materially increase this creepa-ge distance by interposthe unit as showninvFigure 3 where the creepage dis# tance is indicated bythe dotted line 12. -Herel theV creepage distance is over six of the qua-rter inch faces on each side of the groups' of mica sheets and across the =tops.ofetl1e same. The groups of mica sheets and foils in this type of section, .would each be about 1/30 of an inch wide so that the section, Figure 3, would havega total ereepage distance of 11/2.

A further method of increasing the creepage distance isshown in Figure 5. Here two of the sections are placed in series when making up the complete condenser, and the creepage path may then be indicated by the :dotted lines 13 and 14.- Supposing for the sake of illustration that the section, Figure 4 is divided into two sections as shown in Figure 5, thenwhile the distance across the top of the sections remains the same as it was across the single section of Figure 4, the

total creepzxgedistance -from the plate 3 on the left hand section, Figure 5, to the plate ll en the right hand section, Figure-5, is increased by one-half inch.

It should be-ie1neinbere(l'tliat the creepage distance in condensers in the prior art is along a path across all of the condenser' sections in series lbetween the main termina-ls,

A(where. the sections are arranged in series and the conducting plates of each section are in parallel), whereas `in the present invention the creepage distance may be across a single section and is therefore relatively short Hence the necessity of increasing the creepage distance ofl each section as much as possible.

The creepage distance inl some cases may be proportioned in respect to the potential to be applied to the section, and the thickness of the dielectric used therein. In some circuits, if the creepa-ge distance exceeds the puncture point of the dielectric, then the section may be punctured and-ruined without any flash-over occurring. .I therefore calculate for a given case, the necessary free margin of the dielectric aboutthc plates, and so proportion the creepage path to the voltage across the section, that the creepage path may act as a safety spark gap and prevent damage to thevsection.

Having described the construction of the sections, I shall now' describe a complete condenser made` up of a plurality of sections.

I shall first describe a condenser in which each section is in series with the main cir` cuit terminals, a number of the sections being arranged in parallel to form the coxnplete condenser. The=sections are arranged as shown in Figure 6, a number of flexlble conducting strips or section terminals 15, 1G, 17, 18, 19, and 21 being interposed between the sections and serving to conduct current thereto. These section terminals are also designed to act as heat radiating means and conduct heat away from the sections` The sections' indicated by the numerals 22 to 29 inclusive are assembled between a metallic clamp, the ends of which are indicated at 30 and 31 and this clamp holds the sections together under heavy pressure. This clamp is usually connected to the metal casing of the condenser which may have -mounted upon it the main circuit termi- A` main rcircuit terminal-33 is insulated =-f1rom thescasing-,iand to this terminal the sec-1 [.ztion lterminals v15, .17, 19 and 21 are connect-v ed. Itwill' nov(Y be observed that each sec- In Figure 7 Iihaveishown lanother ar- '10 zrangement:itlustratiing'that-tWoor more ot 4ithe'individual sections may1-be-placed in se ries :witlreachf other and arranged inv groups,

' Ythefgro'up`sf=.being connectedwin'parallel. For

'=clearness,.1fha.ve only numberedesome ofthe sections, .the arrangement ioff the 'unnumbered seotionsfbeing obviouszfroin,l the drawing.

I* 'Starting rfnom :the fmafin 'feircuit- 'terminal IBB "the: incoming: circuit. will'tr-averse conto'eondueton- 36 toa'1ju'nctionf-37to conductor 38, through section 39 to one encl'ilof the iclamp'30fandf by Wayoconductor 40 to the mwiniroiitfterminal.32.` Sections andf39 will*v be inl series `as'shownrin' Figureu. .It

'5 willrfbe mndorstmdI that: if: desirable :these v individual sections. may'be of th'etype shown -IA study'foftEigurewill show'the circuit :io connect-ionsaithrough fall of the other sections Vforming the eonipletezcondenser, it being un- `iderstoodathattibeV junctions 37, 4L .and-'42 are -Y not inaiinweircuit -teraninalswbut :are merely point-s tto` Whiclthe variousf. section termi- ;:5 nais, such as l5, areioonnected, and` the conl-i'ductorsf40.and43 are usually'iportionsol the inetaL casing'. y-oonnectinglto the-.metallic `clamp fthe jaws fof-,which are. shown at 3() and 31.

. 4o A.alt .willabembserved .fthat :the qcondenser,

Figure 7, :containsfour 'groupsot sect-ions,

.eacli.:gi:onp being' included eibetween the brackets 44, 45, 4Gl land' .47. 'an'di that between eaehvfot.- theses groups Vv'of Asections A.may ,be

15 interposed theinsulating barriers '48,119 :and

Ainsulating thegroupsof sections from eachother,I Y y hlt will be-noted thatain relation to main v.terminals 32 andY 33, all of `the sections in o group .litarefin series-With the sections in group tiand the sections in; group 46 are in seriesv with the sections-inl group 47,

-'l`.heicomplete condenser Figure 6 or 7 or anyother arrangement of sections that may :beadesirablm maybe-mounted in a suitable casingl 50. As the' complete condenser usually forms a complete unit with its clamp, the latter may be usedto ymount the condenser in the casing, being secured to the G0 latter in any suitable manner.

The clamp is preferably made so it will hold the sections under spring tension to =allow for contraction and expansion. This is accomplished by making the end portions ,c5751. ospring metal suitably shaped, and

binding vthese in restrained: :position by means of piano wire':52'or.inany suitable maamer.

[Themain terminal. 33 may be of any suitlableicharacter suitably insulated from the .casing The casing isprovided` with afsuit- 4able-bottom 53, and atop 54, which 'makes it wax oril tight. y

The'casing is usually filled with suitable insulatingy compound which "completely surrounds all fparts" fof: the condenser rsections, filling any minute'ispaces'iaround fthe fouter edges: of fthe 'mica sheets ycomprising the :condenser sections. I, Y

Y As-the construction ofthe casing and tera minalszdo'not constitutewpart of fthe present ,ffcondenser-:sections ot f members "for spacingv .fthesections apartanda; :flexible metallic q:member interposed fbetween 'the sections for 4the purposey of conductingtcurrent thereto f: andi 'radiating y:heat therefrom, the Ispacing 1 members being conductiveiand isolated. 1'. 2. A condenser, wherein the Idielectric and "conductive sheets'are divided.I inte' groups by .interposed conductive '-blocks .of 1:greater thickness than theI conducting sheets and of smaller area thanithe dielectric sheets.

3. A condenseriicomprisi'ng'afplurality of sections, separator `members-:betweenth'e sections, and terminals extending fbetween `'adzj acentfsections, -saidsections being clamped funden heavyf-.pressure,1= said i members vbeing '.-conduet-ive'and isolated. f f

;4. A condenser andcasing havingcircuit terminals'and a plurality of sections, lthe terminals extending between adjacent sections, each of said 4sections being in parallel with said 'terminals .and :disposed wit-hin said casing, -f and 'separator `imemL-ers also between adjacentlsectionspsaid members being conductive land isolated. i

v 5. A condenser .and-casing' having circuit terminals, a plurality oir-sections, the 'termina-ls extending betweenl adjacent sections, some of said sections being in-'series with each other vand said terminals, and all said sections being disposed\vitliin said casing, and separat-or members also between vad'acent sections, said members being conductive and isolated.

(5. A condenser and easing having a main terminal, a 4plurality of condenser sections lhaving terminals and arranged in said Casing side by side to form a single group,sepa vrater members between the sections, a Connection from the center of said group and yfrom the'ends thereof to said terminal, a vrsecond mainV terminal carried by said casing but insulated therefrom, and a plurality 'of connections from the remaining section terminals to said :insulated main' terminal,

said members beingI conductive and isolated;

7. A condenser comprising three or more sections, separator members between adjacent sections, a clamp for compressing said sections, and a common terminal connected to more than one point in the sections, said members being conductive and isolated.

8. A condenser comprising three or more sections, separator members between adja- `cent sections, each section having a plurality of isolated conducting plates, a terminal for the condenser and a plurality of connections between said terminal and said sections.

9. A condenser comprising a plurality of sections clamped under compression, separator members between adjacent sections, each section comprising a plurality of insulating sheets and conducting plates in intimate contact, and a plurality of connections from said sections to a common terminal carried by the condenser.

10. A condenser consisting of a plurality of sections, separator members between adjacent sections, each section having a plurality of dielectric sheets and isolated conducting plates held in intimate contact with each other under compression and terminals projecting from said sections in opposite directions from the sides thereof.

l1. In a condenser, a casing, a terminal mounted thereon and insulated therefrom, a clamp, a plurality of condenser sections held in said clamp within said casing, and separator members between adjacent sections, some of said sections being connected to the clamp and the remaining sections in circuit with said terminal.

12. In a condenser, a casing, a terminal mounted thereon and insulated therefrom, a plurality of Condenser sections, separator members between adjacent sections, a clamp for the sections whereby they are held under compression, connections from said terminal to some of said sections, and connections between the remaining sections and said casing.

In testimony whereof I affix my signature.

WILLIAM DUBILIER. 

